As you say Ops Procedures was a new subject under JAA/EASA and I used to describe at as dumping ground where they put things they weren't sure about!
The thing you have to be really careful about is the sometimes slightly different numbers regarding minima etc. Ops is EUR-OPs and Air Bore is ICAO.
Ops does contain material from other areas eg. systems & met and I agree with Phil if possible take it last as most of the syllabus would be covered in other areas. It is certainly more practical and flight safety related than Air Bore.
Remember if in doubt the answer is "The Operations Manual"!